1. Field of the Invention
The present invention relates to a lens module, and more particularly, to a lens module of digital camera formed with components such as the filter being fixed on a stand-alone socket using the holder.
2. Description of the Prior Art
Currently on the market, mobile phones (or cell phones) with photo-taking function, digital cameras, and video cameras are all deployed with a lens module. A lens module consists essentially of a lens group, a lens barrel, and an image sensor. FIG. 1 is a views of lens module of the conventional prior art. The lens module consists of the lens group 81, lens barrel 82, and image sensor 83. The lens group 81 are placed inside the lens barrel 82 and include a lens 811 used for focalization and a filter 812 for eliminating specific optical frequency. The image sensor 83 is equipped on one side of the lens barrel 82 and includes one transparent cover plate 831, an image sensing chip 832, and one base board 833.
As shown in FIG. 1, the image sensing chip 832 is fixed on the base board 833 and further packaged between the transparent cover plate 831 and the base board 833 by using the transparent cover plate 831. Thus, the optical image signal entering the lens barrel 82 is firstly focalized through the lenses 811, is filtered by the filter 812, and then passes through the transparent cover plate 831 to the image sensing chip 832. The image sensing chip 832 further converts the optical image signal to the electronic image signal.
For the lens module described above, since an area 821 is to be provided by the lens barrel 82 for placing the filter 812 and the lens barrel 82 is made of plastic, it is easier for the assembly to occupy more space and become heavier. Hence, if the filter placement area 821 can be saved, the lens module can thus become thinner.
Referring to FIG. 2, which is a view of another lens module of the prior art. The lens module comprises a socket 91, a lens unit 92 screwed into the socket 91, an elastic element 93 inserted in the socket 91, a filter 94 fixed inside the socket 91, an image sensing chip 95, and a circuit board 96. This method of assembly allows the lens module to become thinner, but the filter 94 needs to be dispensed to be fixed on the socket 91 and thus the assembling process will be non-reversible. In the actual production process, the assembly may be re-processed because of the tilted optical axis. In the re-assembling process, the filter 94 dispensed and fixed on the socket 91 will be damaged and the cost is thus increased.